The proposed study focuses upon possible hormonal and social factors which determine the psychological significance for the adolescent female of menstruation and menarche. Part I attempts to identify at least one kind of cyclic change in behavior which may be specifically associated with the onset of hormonal variations of the menstrual cycle. It is a longitudinal study in which fluctuations in mood which have previously been shown to occur in adult women are compared with the performance of a control group of adult males. In part II of the study, some of the attitudinal and behavioral correlates of beliefs about menstruation are explored. Previously validated questionnaires are used to determine whether and how beliefs about menstruation are associated with beliefs about other feminine physiological functions, about psychological characteristics associated with masculinity and feminity, about men's and women's roles, and with a measure of self-esteem. The results will be examined to determine whether certain pattern of beliefs and attitudes are related to such socially significant behaviors as religion, occupation, preferred method of contraception, and number of children, and whether these patterns are different for adolescents and adults, males and females. The aim of part II is to examine the social context in which beliefs about menstruation are held, and to begin to determine the cognitive and emotional significance for the individual, and particularly for the adolescent female, of beliefs about menstruation.